Most Awkward Aspect: Pupitar's gas. From Pokemon Emerald: "A Pupitar creates a gas inside its body that it ejects under compression to propel itself like a jet." So it farts, in order to move around. We can't think of a more juvenile mode of transport than that.
Most Awkward Aspect: Magmar's head looks like a butt. Come on, it totally looks like it has a giant butt on the front of its face. And not only that, the butt is on fire. Your teenage years should be about discovering your own style, butt this is not the answer.
Most Awkward Aspect: Gothorita's striking resemblance to a female human adolescent wearing a very specific style of fashion. Obvious goth jokes aside, any animal companion that someone could mistake for your sister deserves a high ranking on this list.
Most Awkward Aspect: Togetic's giant head, suspended on that skinny, brittle neck. You'd think that melon of a noggin would pop right off with a strong breeze. It's also worth noting that when Togetic evolves in Togekiss, it's basically ALL head, with two wings sticking out.
Most Awkward Aspect: EVERYTHING! Gloom is the very embodiment of awkward, teenage angst. It simply couldn't care any less than it already does. There's a dead plant on its head, it drools everywhere, and it always looks like it's sleeping. Now if only it could keep its parents out of its room.